Why no FWB output for SMPS - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 8th June 2012, 02:38 AM   #1
diyAudio Member
 
Join Date: Aug 2010
Default Why no FWB output for SMPS

Does anyone know why a FWB with no center tap is rarely used for a single output with a half or full bridge SMPS. In fact it is not very easy to even buy a ultra fast FWB for SMPS use.
  Reply With Quote
Old 8th June 2012, 04:47 PM   #2
gmarsh is offline gmarsh  Canada
diyAudio Member
 
gmarsh's Avatar
 
Join Date: Apr 2004
Location: Halifax, NS, Canada
Cost/efficiency, I'd imagine.

You're buying twice as many diodes, and 2x the diode drop = 2x the power loss in the output rectifier which means you're buying 2x the heatsinking etc.

Full bridge rectifier output saves a winding in the output transformer, but the full bridge winding has to handle more average current requiring thicker wire or more strands, meaning no copper savings.
  Reply With Quote
Old 8th June 2012, 05:21 PM   #3
diyAudio Member
 
Osvaldo de Banfield's Avatar
 
Join Date: Dec 2011
Location: Barrio Garay,Almirante Brown, Buenos Aires, Argentina
From my (large) experience repairing SMPSīs of various types, also add that it is relatively rare to have a fault in a transformer, while it is normal to find a shorted diode, so reliability is also reduced when more silicon is added.
__________________
LW1DSE
  Reply With Quote
Old 8th June 2012, 05:25 PM   #4
diyAudio Member
 
wrenchone's Avatar
 
Join Date: Feb 2004
Location: Silicon Valley
Adding the extra drop only makes sense at higher output voltages, where you can reap the advantages of a simpler output winding. It also reduces stress on the output diodes - important at higher output voltages. At the usual 5/12/24V levels, it doesn't make a lot of sense.
  Reply With Quote
Old 10th June 2012, 02:02 AM   #5
diyAudio Member
 
Join Date: Aug 2010
I found this out from the book Transformer and Inductor Design 3rd edition by COLONEL WM. T. MCLYMAN. Chapter 7 -4

The total apparent power into the SMPS is the following.

2x the load power for a FWB to FWB converter.

2.414x the load power for FWB to a FWB CT.

2.828X the load power for a CT input and FWB CT output.

Also from Wikipedia, power factor is the ratio of real power to apparent power.

My conclusion is, without power factor correction a FWB output can have lower primary current. However if you use power factor correction, i am not certain how good the above multipliers can be improved.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
What happens with an output choke on a SMPS rickmcinnis Power Supplies 1 10th September 2010 05:30 PM
Quick question about CT and FWB athos56 Tubes / Valves 5 2nd May 2009 04:27 AM
Variable output SMPS Razor-Edge Power Supplies 7 3rd August 2007 11:37 PM
SMPS regulated output MaXiZ Power Supplies 1 24th December 2005 08:10 AM
Non-symetrical SMPS output cm961 Parts 4 21st August 2003 10:27 PM


New To Site? Need Help?

All times are GMT. The time now is 10:03 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2